The present invention relates to message transmission in a CATV (cable television or community antenna television) system.
In CATV systems, a center facility provides programs and commercial broadcast programs on the air to a plurality of subscriber terminal apparatuses via transmission cables. In recent years, services of CATV systems include data transmission. Further, bi-directional CATV systems are now limitedly operated in which each terminal apparatus can transmit a signal (i.e., an up signal) to a center facility. CATV systems operated in schools, hotels, etc. are specifically called "CCTV (closed circuit television) systems".
In the CATV systems, it is sometimes necessary for the center facility to transmit some messages to a particular terminal apparatus. For example, it may be the case that a message is to be transmitted to guests who stay at a hotel for the purpose of attending an international conference to notify them of a schedule change of a symposium on the next day. In such a case, the center facility sends a message command indicating the existence of a message to the related terminal apparatuses. In response, each terminal apparatus informs the user (viewer) of the existence of a message by producing some notification such as flashing of an LED or a buzzer sound. Recognizing this notification, the user turns on his terminal apparatus and TV receiver to see the contents of the message directed to him.
However, in the above CATV systems, if there exists a possibility that a message to be transmitted to a user has a length corresponding to, for instance, three pictures (pages) of the TV receiver screen (in addition to the case of a one-page message), the center facility cannot confirm the user's reception of the entire message, and the user cannot know whether he has received the entire message. Therefore, the confirmation of the reception of all the message should be performed separately, for instance, by telephone. This causes a problem that a message, which is important information, cannot be received positively by all of the intended users.